In which of the following substances will there be an increase in mass when they are exposed to air? Sodium chloride Iron Conc. sulphuric acid Table salt Sodium carbonate crystals

Iron reacts with the oxygen from the air to make iron oxide or rust. So the weight increases in case of iron. This process is called as corrosion or rusting of iron. Concentrated sulphuric acid increases in weight when exposed to air because concentrated sulphuric acid has strong affinity for water and is hygroscopic. It readily absorbs moisture.

A desiccator is an airtight glass vessel with a suitable drying agent (anhydrous calcium chloride) placed at the bottom and it is used for drying solids (substances) in it.

Certain substances when left exposed to atmosphere absorb moisture from the air and become wet. Such substances are called hygroscopic substances and the property is known as hygroscopy. Hygroscopic substances are also called drying agents, e.g. phosphorous pentaoxide, conc. sulphuric acid, anhydrous calcium chloride.

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What is the difference between drying and dehydrating agents?

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Important Questions on Water

MEDIUM

Science>Chemistry>Water>Drying and Dehydrating Agents

In which of the following substances will there be an increase in mass when they are exposed to air?

Sodium chloride
Iron
Conc. sulphuric acid
Table salt
Sodium carbonate crystals

MEDIUM

Science>Chemistry>Water>Drying and Dehydrating Agents

Define desiccator?

MEDIUM

Science>Chemistry>Water>Drying and Dehydrating Agents

Name a blue crystalline salt which on heating changes to white.

EASY

Science>Chemistry>Water>Drying and Dehydrating Agents

Give one example: Hygroscopic solid substance

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Science>Chemistry>Water>Drying and Dehydrating Agents

A phenomenon where a compound absorbs moisture from the atmosphere when it is exposed to it but not enough to form a solution. (Efflorescence / Hygroscopy)

MEDIUM

Science>Chemistry>Water>Drying and Dehydrating Agents

What are desiccating agents or drying agents. Give some examples of it.

EASY

Science>Chemistry>Water>Drying and Dehydrating Agents

Choose the letter corresponding to the correct answer from the choices A, B, C or D given below in the following case:

The salt which is deliquescent:

A. Washing soda

B. Glauber's salt

C. Iron III chloride

D. Alum

MEDIUM

Science>Chemistry>Water>Drying and Dehydrating Agents

What are drying agents or desiccating agents? Why is anhydrous calcium chloride used as a desiccator?

MEDIUM

Science>Chemistry>Water>Drying and Dehydrating Agents

Distinguish between drying agent and dehydrating agent.

EASY

Science>Chemistry>Water>Drying and Dehydrating Agents

Anhydrous calcium chloride is used as a desiccator. Why?

EASY

Science>Chemistry>Water>Drying and Dehydrating Agents

State the term: The substance that can remove hydrogen and oxygen atoms in the ratio of $2 : 1$ (in the form of water) from the compounds. (Catalyst/ Dehydrating agent/ Reagent)

MEDIUM

Science>Chemistry>Water>Drying and Dehydrating Agents

Give the name and formula of two substances for the following.

A basic drying agent.

MEDIUM

Science>Chemistry>Water>Drying and Dehydrating Agents

Take some sugar in a watch glass and add a few drops of concentrated sulphuric acid. Observe the changes. Which is the black substance in the product formed?

MEDIUM

Science>Chemistry>Water>Drying and Dehydrating Agents

What are drying or desiccating agents? Give examples.

HARD

Science>Chemistry>Water>Drying and Dehydrating Agents

What do you observe when crystals of copper sulphate are heated?

MEDIUM

Science>Chemistry>Water>Drying and Dehydrating Agents

Define dehydrating agent?

MEDIUM

Science>Chemistry>Water>Drying and Dehydrating Agents

Explain why fused